“A mountain bike or mountain bicycle (abbreviated MTB) is a bicycle designed for off-road cycling. Mountain bikes share similarities with other bicycles, but incorporate features designed to enhance durability and performance in rough terrain. These typically include a front or full suspension, large knobby tires, more durable wheels, more powerful brakes, straight handlebars, and lower gear ratios for climbing steep grades.”

Source: https://en.wikipedia.org/wiki/Mountain_bike